<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Variable</title>
</head>
<body>
    <button>Press me</button>

    <script>
        var button = document.querySelector('button');

        button.onclick = function() {
            var name = prompt('What is your name?');
            alert('Hello ' + name + ', nice to you!');
        }
    </script>
</body>
</html>